In the construction of reusable liquid crystal thermometers of the type adapted for measuring and indicating the oral temperature of a person, there have been several thermometers either proposed or constructed. For example, U.S. Pat. No. 3,440,882, No. 3,974,317 and No. 3,955,420 disclose different forms of thermometers or temperature measuring and indicating devices and which utilize cholesteric liquid crystal formulations or compositions. The compositions may or may not be microencapsulated and are effective to change in color or in light refraction in response to a change in temperature.
In such an oral thermometer, it is desirable for the body of the thermometer to be unbreakable, non-toxic and easy to clean and sterilize in addition to being easy and convenient to read and feel comfortable in a person's mouth. It is also highly desirable for the thermometer to be durable so that it is not affected by dropping or shaking or vibraion. However, after analyzing the thermometers disclosed in the above patents, it is apparent that none of the thermometers provide all of these desirable features.